Project Summary The risk of developing hepatocellular carcinoma (HCC), a leading cause of death in humans infected with hepatitis virus (HV), is significantly enhanced by dietary exposure to aflatoxin (AF). Also, the carcinogenicity of AF can be promoted with exposure to fumonisin (FB), a common co-contaminant with AF. Importantly, a significant increase in HCC in Texas has been documented in multiple regions of the San Antonio metropolitan area of Bexar County. In a pilot study, we have shown this population is at risk for AF/FB exposure due to the intake of contaminated foods. Thus, innovative strategies for the prevention of HV/AF/FB-induced HCC are high priorities. We have developed a novel approach using a smectite clay (NS) that selectively sorbs AF and FB in the GI tract. In clinical trials in Texas and Ghana, we confirmed the safety and efficacy of NS. In the proposed project, our aims are based on the central hypothesis that intervention with NS will decrease AF/FB exposure in study participants in Bexar County. Our objectives focus on confirming the molecular mechanisms of refined NS and investigating its ability to diminish the incidence of preneoplastic hepatic lesions in a rodent model. Also, biomarkers of toxin exposure will be measured in samples from participants following a 3-month clinical trial. We postulate that this agent will reduce primary exposure to AF/FB and, in turn, reduce the incidence of HCC in vulnerable commumnities in Texas. Between 2002 and 2006, the incidence of HCV infection and HCC in populations in Bexar County was significantly higher compared to other counties in Texas. Therefore, in these populations at risk for HCC, it is desirable to decrease dietary exposure to AF/FB. Mitigating AF/FB exposure using a toxin enterosorbent (i.e., NS clay) represents an innovative, practical, sustainable and environmentally benign approach. Moreover, this strategy is ground-breaking in that a refined smectite clay can be used to decrease the bioavailability of a potent cancer initiator (AF) as well as a potent cancer promoter (FB) by preferentially and tightly sequestering both toxins from the GI tract. The preferred delivery of a therapeutic dose of NS clay may eventually be through its inclusion in common foods such as peanut butter, corn meal, tortillas, or salt (like iodine).